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Small interfering RNA (siRNA) holds great potential to treat many difficult-to-treat diseases, but its delivery remains the central challenge. This study aimed at investigating the suitability of polymer-lipid hybrid nanomedicines (HNMeds) as novel siRNA delivery platforms for locoregional therapy of glioblastoma. Two HNMed formulations were developed from poly(lactic-co-glycolic acid) polymer and a cationic lipid: 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or 3ß-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol (DC-Chol). After characterization of the HNMeds, a model siRNA was complexed onto their surface to form HNMed/siRNA complexes. The physicochemical properties and siRNA binding ability of complexes were assessed over a range of nitrogen-to-phosphate (N/P) ratios to optimize the formulations. At the optimal N/P ratio of 10, complexes effectively bound siRNA and improved its protection from enzymatic degradation. Using the NIH3T3 mouse fibroblast cell line, DOTAP-based HNMeds were shown to possess higher cytocompatibility in vitro over the DC-Chol-based ones. As proof-of-concept, uptake and bioefficacy of formulations were also assessed in vitro on U87MG human glioblastoma cell line expressing luciferase gene. Complexes were able to deliver anti-luciferase siRNA and induce a remarkable suppression of gene expression. Noteworthy, the effect of DOTAP-based formulation was not only about three-times higher than DC-Chol-based one, but also comparable to lipofectamine model transfection reagent. These findings set the basis to exploit this nanosystem for silencing relevant GB-related genes in further in vitro and in vivo studies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The development of smart delivery systems able to deliver and target a drug to the site of action is one of the major challenges in the field of pharmaceutical technology. The surface modification of nanocarriers, such as liposomes, is widely investigated either for increasing the blood circulation time (by pegylation) or for interacting with specific tissues or cells (by conjugation of a selective ligand as a monoclonal antibody, mAb). Microscopical analysis thereby is a useful approach to evaluate the morphology and the size owing to resolution and versatility in defining either surface modification or the architecture and the internal structure of liposomes. This contribution aims to connect the outputs obtained by transmission electron (TEM) and atomic force (AFM) microscopical techniques for identifying the modifications on the liposomal surface. To reach this objective, we prepared liposomes applying two different pegylation technologies and further modifying the surface by mAb conjugation. This work demonstrates the feasibility to apply the combined approach (TEM and AFM analysis) in the evaluation of the efficacy of a surface engineering process.

Metronomic chemotherapy supports the idea that long-term, sustained, constant administration of chemotherapeutics, currently not achievable, could be effective against numerous cancers. Particularly appealing are liposomal formulations, used to solubilize hydrophobic therapeutics and minimize side effects, while extending drug circulation time and enabling passive targeting. As liposome alone cannot survive in circulation beyond 48 h, sustaining their constant plasma level for many days is a challenge. To address this, we develop, as a proof of concept, an implantable nanochannel delivery system and ultra-stable PEGylated lapatinib-loaded liposomes, and we demonstrate the release of intact vesicles for over 18 d. Further, we investigate intravasation kinetics of subcutaneously delivered liposomes and verify their biological activity post nanochannel release on BT474 breast cancer cells. The key innovation of this work is the combination of two nanotechnologies to exploit the synergistic effect of liposomes, demonstrated as passive-targeting vectors and nanofluidics to maintain therapeutic constant plasma levels. In principle, this approach could maximize efficacy of metronomic treatments., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An outstanding aspect of pharmaceutical nanotechnology lies in the characterization of nanocarriers for targeting of drugs and other bioactive agents. The development of microscopic techniques has made the study of the surface and systems architecture more attractive. In the field of pharmaceutical nanosystems, researchers have collected vital information on size, stability, and bilayer organization through the microscopic characterization of liposomes. This paper aims to compare the results obtained by atomic force microscopy, environmental scanning electron microscopy, transmission electron microscopy, and confocal laser scanning microscopy to point out the limits and advantages of these applications in the evaluation of vesicular systems. Besides this comparative aim, our work proposes a simple confocal laser scanning microscopy procedure to rapidly and easily detect the liposomal membrane.

Aims: To develop an appropriate liposomal formulation for gene delivery against primary effusion lymphoma (PEL), a herpesvirus HHV8-associated B-cell lymphoma., Materials & Methods: Cationic, cationic PEGylated and cationic PEGylated anti-CD138 liposomes (ILp) linking a monoclonal antibody expressed on PEL cells were prepared by a thin layer evaporation method, followed by extrusion technique. The formulations were mixed with a model oligonucleotide to form the lipoplexes and tested on a BCBL-1 cell (a PEL cell line). The transfection efficiency was evaluated by flow cytometry and confocal laser scanning microscopy analysis., Results: Based on antigen-antibody interaction, ILp mediated a specific gene delivery as shown by a significant increase in the transfection rate and a localized internalization of the oligonucleotide, in comparison with cationic liposomes and cationic PEGylated liposomes., Conclusion: ILp could be proposed as effective carriers for oligonucleotide transfer in BCBL-1 cells. In vitro experimental results encourage us to further test the in vivo therapeutic potential of ILp for specific delivery of antitumoral agents.

Despite of the several approaches applied to the physicochemical characterization of liposomes, few techniques are really useful to obtain information about the surface properties of these colloidal drug-delivery systems. In this paper, we demonstrate a possible new application of tapping mode atomic force microscopy (AFM) to discriminate between conventional and pegylated liposomes. We showed that the differences on liposomal surface properties revealed by the phase images AFM approach well correlate with the data obtained using classical methods, such as light scattering, hydrodynamic, and nuclear magnetic resonance analysis.

The relatively hydrophilic bile acid, ursodeoxycholic acid (UDCA), was used as an additive to DOTAP cationic liposomes to evaluate the effect on the cellular uptake of an oligonucleotide. Nuclear magnetic resonance studies were applied to estimate the relative amount of incorporated UDCA into the lipidic bilayers. DOTAP or DOTAP-UDCA vesicles (MixVes; DOTAP/UDCA molar ratios 1:0.25, 1:0.5, 1:1, and 1:2) formed complexes with 5'-fluorescein conjugated 29-mer phosphorothioate oligonucleotides (PS-ODNs) and studied using gel electrophoresis. In addition, the complexes were tested after transfection to assess the cellular uptake and the localization of the oligo in a HaCaT cell line by the use of cytofluorimetric and confocal microscopic analysis. DOTAP lipid formulated in the presence of a defined amount of UDCA forms more stable, flexible, and active MixVes. In particular, the MixVes at 1:0.25 and 1:0.5 molar ratios increase and modify the cellular uptake of PS-ODNs if compared with DOTAP liposomes 3 hours after the transfection studies. Moreover, the in vitro data suggest that these new formulations are not toxic.

Liposomes are considered very promising delivery systems for antisense therapeutic approach, offering drug protection and facilitating oligonucleotide cell internalization. The present study was aimed to investigate the influence of phospholipid composition of the liposomal systems both on the encapsulation and on the oligonucleotide carrier capacity in vitro. Liposomes composed of neutral (phosphatidylcholine, cholesterol and dioleoylphosphatidylethanolamine) and/or cationic lipids (N-(1-(2,3-dioleoyloxy)propyl)-N,N,N-trimethylammonium chloride salt, DOTAP) with different molar ratios were complexed with 5' fluorescein conjugated 29-mer phosphorothioate oligonucleotide (PS-ODN). The interaction was evaluated using atomic force microscopy (AFM), gel electrophoresis and HPLC analysis. Cytofluorimetric analysis and fluorescence microscopy were applied to evaluate the uptake and intracellular distribution of fluorescently labelled PS-ODN after transfection in two cell lines, COS I (fibroblast cell) and HaCaT (immortalized keratinocyte cell). The AFM studies reveal that the liposome/PS-ODN interaction leads the formation of a new irregular structure that completely hides the PS-ODN. Gel electrophoresis experiments and HPLC analysis have clearly demonstrated that also neutral liposomes are able to keep a little amount of PS-ODN but without strain to the complexation; the interaction was weak and rapidly destabilized when the complex was added to the cells. Transfection experiments performed with different incubation times show that DOTAP liposomes increase the rate of cellular uptake of PS-ODN and seem to influence its intracellular distribution in COS I cells where the oligonucleotide looks localized in nucleoli. Similar behaviour, at a lesser extent, is exhibited in HaCaT cells.

The direct evaluation of the heterogeneity of the particle population of nanometric drug delivery systems as liposomes is difficult to achieve owing to the dimension and the carrier characteristics. The influence of the lipidic ratio and composition on the physical stability of liposomes during their storage was investigated using atomic force microscopy (AFM) and photon correlation spectroscopy (PCS). Liposomes were made by a mixture of different lipids and obtained using distinct methods of preparation. AFM images, acquired immediately after the deposition of the sample on mica surface, clearly showed the spherical shape of the lipidic vesicles. In all the 7 months of the experiment, the average sizes of the different liposomes evaluated using the two techniques were comparable. According to PCS analysis, AFM images confirmed that almost all the diversified vesicular systems tended to form aggregates during their storage; this loss of stability was strengthened by the increase of polydispersity index value. The different behaviours observed were to ascribe to the lipidic composition more than the methods of liposome preparation. In conclusion, AFM technique owing to the relative simplicity cold be useful for the technological control of size distribution profile according to the preparative factors and moreover to the batch-to-batch reproducibility.

Liposomes loaded with ketorolac tromethamine salt were prepared by using a thin layer evaporation method. The physical properties of liposomes were studied by using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The relationship between lipid composition, encapsulation efficiency, vesicle size, and the release of ketorolac tromethamine-loaded liposomes was studied. The drug content was found to be dependent on the lipidic composition used in the preparations and, in particular, vesicles containing both cationic lipids (dimethyldioctadecylammonium bromide and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride), and phosphatidylcholine had a higher entrapped efficiency than liposomes with phosphatidylcholine alone or in the presence of cholesterol. Finally, the cationic liposomes appear to be useful as carriers for ketorolac tromethamine to control its in vitro release.

Cationic liposomes spontaneously interact with the negatively charged DNA to form a stable complex that promotes the gene transfer to cells. The mode of formation and the size of cationic liposomes/DNA complexes were investigated using the atomic force microscopy (AFM). Also the most important physical-chemical factors involved in cationic liposome-mediated gene transfection, e.g. size and lipidic composition, were evaluated through the transfection of complexes with different liposomes/DNA molar ratio into three types of cultured cells. Cationic liposomes, composed of a neutral lipid (phosphatidilcoline), a cationic lipid dimethyldioctadecylammonium bromide (DDAB), a co-lipid 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) and a phospholipid derivative of polyethylene glycol (DSPE-mPEG) at different molar ratio, were mixed with a plasmid pCMVbeta to form liposomes/DNA complexes. We have demonstrated that the complexes were made by complicated structures in which the liposomes tend to aggregate and the DNA is surrounded by lipidic material. In vitro transfection efficiency by liposomes/plasmid pCMVbeta complexes was found to depend on the kind of lipid associated in the liposomes and the liposomes/DNA mixing ratio. The importance of associating DOPE in cationic liposomes was confirmed; this co-lipid is able to improve the ability of cationic liposomes to transfect cells but in addition, the AFM images and the EtBr fluorescence experiments have suggested that this lipid can also play an important role to facilitate the formation of stable liposomes, which efficaciously protect the DNA by nuclease digestion.

Abstract: At present, liposomes play a significant role as drug delivery vehicles being considered very promising for gene therapeutics. The in vivo application of these drug delivery systems widely depends on their physico-chemical and technological characteristics such as the structure, the shape, the size distribution, the surface modification and the drug interaction. To describe the liposomes, different analytical techniques were used. In this paper, we reviewed the application of the atomic force microscopy (AFM), one of the most commonly applied scanning probe microscopy (SPM) techniques, in the description of liposome. The advantages and limitations of these techniques are discussed comparing the reported data with those referred to other well-know microscopical and spectroscopical techniques such as transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS). A detailed description of the application of AFM to evaluate the formation and the geometry of liposomes/DNA complexes is presented. [Copyright &y& Elsevier]

We evaluated whether specifically and directly targeting human antigen R (HuR), a member of embryonic lethal abnormal vision (ELAV) proteins family, may represent a new potential therapeutic strategy to manage diabetic retinopathy. Nanosystems loaded with siRNA silencing HuR expression (lipoplexes), consisting of solid lipid nanoparticles (SLN) and liposomes (SUV) were prepared. Photon correlation spectroscopy analysis, Zeta potential measurement and atomic force microscopy (AFM) studies were carried out to characterize the complexation of siRNA with the lipid nanocarriers. Nanosystems were evaluated by using AFM and scanning electron microscopy. The lipoplexes were injected into the eye of streptozotocin (STZ)-induced diabetic rats. Retinal HuR and VEGF levels were detected by Western blot and ELISA, respectively. Retinal histology was also carried out. The results demonstrated that retinal HuR and VEGF are significantly increased in STZ-rats and are blunted by HuR siRNA treatment. Lipoplexes with a weak positive surface charge and with a 4:1 N/P (cationic lipid nitrogen to siRNA phosphate) ratio exert a better transfection efficiency, significantly dumping retinal HuR and VEGF levels. In conclusion, we demonstrated that siRNA can be efficiently delivered into the rat retina using lipid-based nanocarriers, and some of the lipoplexes loaded with siRNA silencing HuR expression are potential candidates to manage retinal diseases. [ABSTRACT FROM AUTHOR]

Abstract: Cidofovir is an antiviral drug active as antitumoral agent a high doses against the Primary Effusion Lymphoma, a herpesvirus HHV8-associated B-cell lymphoma. A novel polymeric/lipidic hybrid system, consisting in a specific combination of biocompatible materials, capable to build a crossbred between polymeric particles and liposomes were prepared and used to stabilize and deliver the drug, unsuccessfully formulated into several types of carriers. This innovative cidofovir-delivering system has structurally been characterized in comparison to multilamellar liposomes and polymeric particles, and then tested for antitumoral efficacy against tumor cells (BCBL-1 cell line). The results demonstrated the improving of drug stability and encapsulation efficiency and suggested that polymeric/lipidic hybrid system could be promising to improve the antitumoral effect of cidofovir even at lower doses. [Copyright &y& Elsevier]